Neuraminidase (Influenza A and B) (NA)

Neuraminidase (NA) is one of the two major surface glycoproteins found on the envelope of influenza A and B viruses, the other being hemagglutinin. It is a tetrameric enzyme that functions as a sialidase, catalyzing the removal of terminal sialic acid residues from host cell receptors and viral glycoproteins (UniProt: P03468). This enzymatic activity is critical for the release of newly synthesized virions from the host cell membrane, preventing the virus from being trapped by its own hemagglutinin or by mucus in the respiratory tract (PubMed: 24601504). In influenza vaccines, NA is an important antigen that contributes to the breadth and duration of the immune response, although it is often present in varying amounts compared to hemagglutinin. Therapeutic targeting of NA with neuraminidase inhibitors like oseltamivir and zanamivir is a standard clinical approach to reduce the duration and severity of influenza symptoms by limiting viral spread within the host (NIH: StatPearls).

Other names

SialidaseExo-alpha-sialidaseAcetylneuraminyl hydrolaseViral neuraminidaseNA protein

Neuraminidase inhibitors competitively bind to the active site of the viral neuraminidase enzyme, preventing the cleavage of terminal sialic acid residues on host cell receptors and viral glycoproteins. This action traps newly formed virions on the surface of the infected cell, preventing their release and subsequent spread to uninfected cells (StatPearls, 2023; PubMed: 22230238).